Transmission apparatus, transmission method, reception apparatus, and reception method

ABSTRACT

Connection with an apparatus with a lower standard is easily performed. A digital signal to which coding has been performed is transmitted to an external device by a differential signal through a plurality of channels via a transmission path. In this case, a digital signal to which first coding has been performed and from which clock extraction is not available is transmitted through a part of the plurality of channels, and a digital signal to which second coding has been performed and from which clock extraction is available is transmitted through the other channels of the plurality of channels. A reception side processes the digital signal received through the plurality of channels on the basis of the clock extracted from the digital signal received through any one of other channels.

TECHNICAL FIELD

The present invention relates to a transmission apparatus, atransmission method, a reception apparatus, and a reception method, andspecifically, relates to a transmission apparatus which transmits adigital signal such as a video by a differential signal via atransmission path.

BACKGROUND ART

In recent years, a high definition multimedia interface (HDMI) has beenwidely used as a digital interface for connecting consumer electronics(CE) devices, and the HDMI has been the de facto standard in the field.In the HDMI standard, signals of a video, audio, and control aretransmitted as digital signals by using three data differential linepairs (TMDS Channel 0/1/2). Note that the “HDMI” is the registeredtrademark.

Now, the maximum value determined in the HDMI standard as a transmissionspeed of the digital signal is 10.2 Gbps. In consideration of theadoption to a video signal of a 4k2k (QFHD) and a video signal withcontents having a higher image quality, the above value of the HDMI isrequired to be extended to the highest value such as 15 Gbps and 20 Gbpsin the current standard in the future.

To speed-up the HDMI, it is considered to increase the number of thedata differential line pairs from three for now to four or more. Theapplicant has proposed a technology for increasing the number of thedata differential line pairs to six (Patent Document 1).

CITATION LIST Patent Document Patent Document 1: Japanese PatentApplication Laid-Open No. 2012-75067 SUMMARY OF THE INVENTION Problemsto be Solved by the Invention

A purpose of the present technology is to easily perform connection withan apparatus with a lower standard.

Solutions to Problems

A concept of the present technology is a transmission apparatusincluding a digital signal transmission unit which transmits a digitalsignal to which coding has been performed to an external device by adifferential signal through a plurality of channels via a transmissionpath. In the transmission apparatus, the digital signal transmissionunit transmits a digital signal to which first coding has been performedand from which clock extraction is not available through a part of theplurality of channels and transmits a digital signal to which secondcoding has been performed and from which clock extraction is availablethrough the other channels of the plurality of channels.

In the present technology, the digital signal transmission unittransmits the digital signal to which coding has been performed to theexternal device by the differential signal through the plurality ofchannels via the transmission path. Here, the digital signal to whichthe first coding has been performed and from which clock extraction isnot available is transmitted through a part of the plurality ofchannels, and the digital signal to which the second coding has beenperformed and from which clock extraction is available is transmittedthrough the other channels of the plurality of channels.

For example, the first coding may be TMDS coding. Also, for example,both the first coding and the second coding may be 8 bit/10 bitconversion coding. Also, for example, the transmission path may be anHDMI cable, the number of a part of the channels may be three, and thenumber of other channels may be three.

In this way, according to the present technology, the digital signal towhich the first coding has been performed and from which the clockextraction is not available is transmitted through a part of theplurality of channels, and the digital signal to which the second codinghas been performed and from which clock extraction is available istransmitted through the other channels of the plurality of channels.Therefore, connection with an apparatus with a lower standard for usingthe digital signal to which the first coding has been performed can beeasily performed. That is, even when the apparatus is configured to beconnectable with the apparatus with a lower standard, it is notnecessary to additionally perform the first coding.

Also, another concept of the present technology is a reception apparatusincluding a digital signal reception unit which receives a digitalsignal to which coding has been performed from an external device by adifferential signal through a plurality of channels via a transmissionpath. In the reception apparatus, the digital signal reception unitreceives a digital signal to which first coding has been performed andfrom which clock extraction is not available through a part of theplurality of channels and receives a digital signal to which secondcoding has been performed and from which clock extraction is availablethrough other channels of the plurality of channels. The receptionapparatus further includes a processing unit which processes the digitalsignal received through the plurality of channels on the basis of aclock extracted from the digital signal received through any one of theother channels.

According to the present technology, the digital signal reception unitreceives the digital signal to which the coding has been performed fromthe external device by the differential signal through the plurality ofchannels via the transmission path. Here, the digital signal to whichthe first coding has been performed and from which clock extraction isnot available is received through a part of the plurality of channels,and the digital signal to which the second coding has been performed andfrom which clock extraction is available is received through the otherchannels of the plurality of channels. The processing unit processes thedigital signal received through the plurality of channels on the basisof the clock extracted from the digital signal received through any oneof the other channels.

In this way, according to the present technology, the digital signalreceived through the plurality of channels is processed on the basis ofthe clock extracted from the digital signal received through any one ofthe other channels. Therefore, the digital signal received through apart of the plurality of channels can be excellently processed withoutreceiving the clock.

Also, still another concept of the present technology is a transmissionapparatus including a digital signal transmission unit which transmits adigital signal to which coding has been performed to an external deviceby a differential signal through a plurality of channels via atransmission path. In the transmission apparatus, the digital signaltransmission unit transmits the digital signal by selecting one of afirst mode and a second mode, and the first mode is a mode fortransmitting a digital signal to which first coding has been performedand from which clock extraction is not available through a predeterminednumber of first channels and transmitting a digital signal to whichsecond coding has been performed and from which clock extraction isavailable through a predetermined number of second channels, and thesecond mode is a mode for transmitting a digital signal to which thefirst coding has been performed through the predetermined number offirst channels and transmitting a clock through a single third channelcorresponding to any one of the predetermined number of second channels.

In the present technology, the digital signal transmission unittransmits the digital signal to which coding has been performed to theexternal device by the differential signal through the plurality ofchannels via the transmission path. Here, the digital signaltransmission unit transmits the digital signal by selecting one of thefirst mode and the second mode.

In the first mode, the digital signal to which the first coding has beenperformed and from which the clock extraction is not available istransmitted through the predetermined number of first channels, and thedigital signal to which the second coding has been performed and fromwhich clock extraction is available is transmitted through thepredetermined number of second channels. In the second mode, the digitalsignal to which the first coding has been performed is transmittedthrough the predetermined number of first channels, and the clock istransmitted through the single third channel corresponding to any one ofthe predetermined number of second channels.

For example, the first coding may be TMDS coding. Also, for example,both the first coding and the second coding may be 8 bit/10 bitconversion coding. Also, for example, the transmission path may be theHDMI cable. The number of the first channels may be three, and thenumber of the second channels may be three.

In this way, according to the present technology, the digital signal istransmitted by selecting one of the first mode and the second mode.Therefore, by selecting the first mode, a signal can be transmitted witha high data rate. By selecting the second mode, connection with theapparatus with a lower standard for using the digital signal to whichthe first coding has been performed can be performed.

Furthermore, in the present technology, for example, a mode determiningunit which determines whether the external device and the transmissionpath are compliant with the first mode and a control unit which controlsmode selection by the digital signal transmission unit on the basis ofthe determination by the mode determining unit may be further included.In this case, when the external device and the transmission path arecompliant with the first mode, the transmission in the first mode isperformed, and wrong signal transmission can be avoided.

Also, in the present technology, for example, the channels of thepredetermined number of second channels other than the single channelcorresponding to the third channel may be AC coupled with thetransmission path. The AC coupled channel is advantageous to thehigh-speed operation, and an advantage over the other channel issecured.

Also, yet another concept of the present technology is a receptionapparatus including a digital signal reception unit which receives adigital signal to which coding has been performed from an externaldevice by a differential signal through a plurality of channels via atransmission path. In the reception apparatus, the digital signalreception unit receives the digital signal by selecting one of a firstmode and a second mode. The first mode is a mode for receiving a digitalsignal to which first coding has been performed and from which clockextraction is not available through a predetermined of number of firstchannels and receiving a digital signal to which second coding has beenperformed and from which clock extraction is available through apredetermined number of second channels, and the second mode is a modefor receiving a digital signal to which the first coding has beenperformed through the predetermined number of first channels andreceiving a clock through a single third channel corresponding to anyone of the predetermined number of second channels. The receptionapparatus further includes a processing unit which processes the digitalsignal received through the predetermined number of first channels andsecond channels on the basis of the clock extracted from the digitalsignal received through any one of the predetermined number of secondchannels in the first mode and processes the digital signal receivedthrough the predetermined number of first channels on the basis of theclock received through the third channel in the second mode.

According to the present technology, the digital signal reception unitreceives the digital signal to which the coding has been performed fromthe external device by the differential signal through the plurality ofchannels via the transmission path. Here, the digital signal receptionunit receives the digital signal by selecting one of the first mode andthe second mode.

In the first mode, the digital signal to which the first coding has beenperformed and from which the clock extraction is not available isreceived through the predetermined number of first channels, and thedigital signal to which the second coding has been performed and fromwhich the clock extraction is available is received through thepredetermined number of second channels. In the second mode, the digitalsignal to which the first coding has been performed is received throughthe predetermined number of first channels, and the clock is receivedthrough the single third channel corresponding to any one of thepredetermined number of second channels.

The processing unit processes the digital signal received through thepredetermined number of first channels and second channels on the basisof the clock extracted from the digital signal received through any oneof the predetermined number of second channels in the first mode. Also,the processing unit processes the digital signal received through thepredetermined number of first channels on the basis of the clockreceived through the third channel in the second mode.

For example, both the first coding and the second coding may be 8 bit/10bit conversion coding. Also, for example, the transmission path may bethe HDMI cable. The number of the first channels may be three, and thenumber of the second channels may be three.

In this way, according to the present technology, either one of thefirst mode and the second mode is selected, and the digital signal isreceived. Therefore, by selecting the first mode, a signal can betransmitted with a high data rate. By selecting the second mode,connection with the apparatus with a lower standard for using thedigital signal to which the first coding has been performed can beperformed.

Furthermore, in the present technology, for example, the channels of thepredetermined number of second channels other than the single channelcorresponding to the third channel may be AC coupled with thetransmission path. The AC coupled channel is advantageous to thehigh-speed operation, and an advantage over the other channel issecured.

Also, in the present technology, for example, the control unit may beincluded which controls mode selection by the digital signaltransmission unit on the basis of control information transmitted fromthe external device. In this case, since the mode which is compliantwith the mode selection by the external device is selected, the digitalsignal transmitted from the external device can be appropriatelyreceived.

Effects of the Invention

According to the present technology, connection with an apparatus with alower standard can be easily performed. The effects described herein areonly exemplary and not limited to these. Also, there may be anadditional effect.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an exemplary configuration of an AV systemaccording to an embodiment of the present invention.

FIGS. 2(a) to 2(d) are diagrams of exemplary combinations of a sourcedevice, an HDMI cable, and a sink device.

FIG. 3 is a diagram of an exemplary configuration (at the time of anoperation mode of a current HDMI) of a data transmitting unit of thesource device and a data receiving unit of the sink device.

FIG. 4 is a diagram of an exemplary configuration (at the time of anoperation mode of a new HDMI) of a data transmitting unit of the sourcedevice and a data receiving unit of the sink device.

FIG. 5 is a block diagram of an exemplary configuration of an HDMItransmitter.

FIG. 6 is a block diagram of an exemplary configuration of an HDMIreceiver.

FIG. 7 is a diagram of an exemplary structure of TMDS transmission data.

FIGS. 8(a) and 8(b) are diagrams indicating a comparison between pinassignments of the current HDMI (Type A) and the new HDMI.

FIGS. 9(a) and 9(b) are diagrams of pin arrangements of receptacles ofthe source devices and the sink devices of the current HDMI and the newHDMI.

FIGS. 10(a) and 10(b) are diagrams of an exemplary structure of acurrent HDMI cable.

FIG. 11 is a diagram of an exemplary structure of a new HDMI cable.

FIG. 12 is a flowchart of an exemplary procedure for controlling anoperation mode by a control unit of the source device.

FIGS. 13(a) to 13(c) are diagrams of exemplary UI screens displayed on adisplay unit (display) by the control by the control unit of the sourcedevice.

FIG. 14 is a flowchart of another example of a procedure for controllingan operation mode by the control unit of the source device.

FIG. 15 is a diagram of exemplary flag information newly defined inEDID.

FIG. 16 is a diagram to describe a method for determining whether thecable in the control unit is compliant with the new HDMI.

MODE FOR CARRYING OUT THE INVENTION

A mode for carrying out the present invention (referred to as“embodiment”) is described below. Note that the description is made inthe following order.

1. Embodiment

2. Modification

1. Embodiment

[Exemplary Configuration of AV System]

FIG. 1 is a diagram of an exemplary configuration of an audio and visual(AV) system 100 according to an embodiment. The AV system 100 includes asource device 110 and a sink device 120 connected to each other. Thesource device 110 is an AV source such as a game machine, a disk player,a set top box, a digital camera, and a mobile phone. The sink device 120is, for example, a television receiver and a projector.

The source device 110 is connected to the sink device 120 via a cable200. The source device 110 includes a receptacle 111, to which a datatransmitting unit 112 is connected, for configuring a connector. Thesink device 120 includes a receptacle 121, to which a data receivingunit 122 is connected, for configuring a connector. Also, a plug 201 forconfiguring the connector is provided at one end of the cable 200, and aplug 202 for configuring the connector is provided at the other end. Theplug 201 at one end of the cable 200 is connected to the receptacle 111of the source device 110, and the plug 202 at the other end of the cable200 is connected to the receptacle 121 of the sink device 120.

The source device 110 includes a control unit 113. The control unit 113controls the entire source device 110. In the present embodiment, thedata transmitting unit 112 of the source device 110 is compliant withboth the current HDMI and the new HDMI. When it is determined that thecable 200 is compliant with the new HDMI and the sink device 120 iscompliant with the new HDMI, the control unit 113 controls the datatransmitting unit 112 to operate in an operation mode of the new HDMI.On the other hand, at least when it is determined that the sink device120 is compliant with the current HDMI or that the cable 200 iscompliant with the current HDMI, the control unit 113 controls the datatransmitting unit 112 to operate in the operation mode of the currentHDMI.

The sink device 120 includes a control unit 123. The control unit 123controls the entire sink device 120. In the present embodiment, the datareceiving unit 122 of the sink device 120 is compliant with the currentHDMI or both the current HDMI and the new HDMI. When the data receivingunit 122 is compliant with both the current HDMI and the new HDMI, thecontrol unit 123 controls the data receiving unit 122 to operate in theoperation mode same as that of the data transmitting unit 112 of thesource device 110. In this case, the control unit 123 controls theoperation mode of the data receiving unit 122, for example, on the basisof a determination result on the operation mode transmitted through aline such as a CEC from the source device 110. The cable 200 iscompliant with the current HDMI or the new HDMI.

In the AV system 100 illustrated in FIG. 1, when the cable 200 iscompliant with the new HDMI and the sink device 120 is compliant withboth the current HDMI and the new HDMI as illustrated in FIG. 2(a), datais transmitted with the new HDMI. At this time, the data transmittingunit 112 of the source device 110 and the data receiving unit 122 of thesink device 120 are controlled to operate in the operation mode of thenew HDMI.

Also, in the AV system 100 illustrated in FIG. 1, at least when thecable 200 is compliant with the current HDMI or when the sink device 120is compliant with the current HDMI as illustrated in FIGS. 2(b) to 2(d),data is transmitted with the current HDMI. At this time, the datatransmitting unit 112 of the source device 110 is controlled to operatein the operation mode of the current HDMI. Also, the data receiving unit122 of the sink device 120 which is compliant with both the current HDMIand the new HDMI is controlled to operate in the operation mode of thecurrent HDMI.

Furthermore, in a case of FIG. 2(b), when the cable 200 can perform newHDMI data transmission by lowering a data transfer rate and the like,data may be transmitted in the new HDMI mode.

“Exemplary Configurations of Data Transmitting Unit and Data ReceivingUnit”

FIGS. 3 and 4 are exemplary configurations of the data transmitting unit112 of the source device 110 and the data receiving unit 122 of the sinkdevice 120 in the AV system 100 in FIG. 1. The data transmitting unit112 transmits a differential signal corresponding to uncompressed videodata for one screen to the data receiving unit 122 in a single directionthrough a plurality of channels in an effective video period (alsoreferred to as “active video period”).

Here, the effective video period is a period from one verticalsynchronizing signal to a next vertical synchronizing signal other thana horizontal retrace period and a vertical retrace period. Also, thedata transmitting unit 112 transmits at least a differential signalcorresponding to audio data and control data associated with video dataand other auxiliary data to the data receiving unit 122 in a singledirection through a plurality of channels in the horizontal retraceperiod or the vertical retrace period.

The data receiving unit 122 receives the differential signal, whichcorresponds to the video data, transmitted from the data transmittingunit 122 in a single direction through the plurality of channels in theactive video period. Also, the data receiving unit 122 receives thedifferential signal, which corresponds to the audio data and the controldata, transmitted from the data transmitting unit 112 in a singledirection through the plurality of channels in the horizontal retraceperiod or the vertical retrace period.

An HDMI system including the data transmitting unit 112 and the datareceiving unit 122 has following transmission channels. The HDMI systemincludes a differential signal channel as a transmission channel. Thenumber of the differential signal channels for transmitting the digitalsignal such as video data is three in the current HDMI. However, thenumber of the differential signal channels is six in the new HDMI.

The differential signal channel in the operation mode of the currentHDMI is described. As illustrated in FIG. 3, three TMDS channels #0 to#2 are used as transmission channels to serially transmit the video dataand the audio data from the data transmitting unit 112 to the datareceiving unit 122 in a single direction synchronously with a pixelclock. Also, a TMDS clock channel is used as a transmission channel fortransmitting a TMDS clock. These channels are DC coupled with the cable200.

For example, an HDMI transmitter 81 of the data transmitting unit 112performs TMDS coding to uncompressed video data, and after that,converts it to the corresponding differential signal. Then, the threeTMDS channels #0 to #2 serially transmit the differential signals to thedata receiving unit 122, which is connected via the cable 200, in asingle direction. Also, the HDMI transmitter 81 performs the TMDS codingto the audio data associated with the uncompressed video data, necessarycontrol data, and other auxiliary data, and after that, converts them tothe corresponding differential signals. Then, the three TMDS channels #0to #2 serially transmit the differential signals to the data receivingunit 122 in a single direction.

In addition, the HDMI transmitter 81 transmits the TMDS clock (pixelclock) synchronized with the video data transmitted through the threeTMDS channels #0 to #2 to the data receiving unit 122, which isconnected via the cable 200, through the TMDS clock channel. Here, asingle TMDS channel #i (i=0, 1, 2) transmits 10-bit data in a singleTMDS clock.

Here, the TMDS coding is 8 bit/10 bit conversion coding for converting8-bit data into 10-bit data. With the TMDS coding, a bad effect such asunnecessary radiation is reduced by reducing transition points from theprevious data, and a DC balance is maintained. Therefore, since arun-length of coding cannot be theoretically secured, it is necessary toform DC coupling and to separately transmit a clock.

An HDMI receiver 82 of the data receiving unit 122 receives thedifferential signals which correspond to the video data and thedifferential signals corresponding to the audio data and the controldata transmitted from the data transmitting unit 112 in a singledirection through the TMDS channels #0 to #2. In this case, the HDMIreceiver 82 synchronizes the differential signal with the TMDS clock(pixel clock) transmitted from the data transmitting unit 112 throughthe TMDS clock channel to receive it.

Next, the differential signal channel in the operation mode of the newHDMI is described. As illustrated in FIG. 4, six TMDS channels #0 to #5are used as transmission channels to serially transmit the video dataand the audio data from the data transmitting unit 112 to the datareceiving unit 122 in a single direction synchronously with a pixelclock. Note that, in the new HDMI, transmission of the TMDS clock isomitted, and a self-clock system for reproducing the clock from thereceived data is employed at the reception side.

Here, the TMDS channels #0 to #2 respectively correspond to the TMDSchannels #0 to #2 in the operation mode of the current HDMI. Also, theTMDS channel #3 corresponds to the TMDS clock channel in the operationmode of the current HDMI. That is, the four channels are used in theoperation mode of the current HDMI and the operation mode of the newHDMI in common. Although the four channels are DC coupled with the cable200 as described above, the TMDS channels #4 and #5 are AC coupled withthe cable 200. An advantage to a high-speed operation is secured.

For example, the HDMI transmitter 81 of the data transmitting unit 112converts the uncompressed video data to the corresponding differentialsignal and serially transmits the signal to the data receiving unit 122which is connected via the cable 200 through the six TMDS channels #0 to#5 in a single direction. Also, the HDMI transmitter 81 converts theaudio data associated with the uncompressed video data, necessarycontrol data, and other auxiliary data to the corresponding differentialsignals and serially transmits the differential signals to the datareceiving unit 122 through the six TMDS channels #0 to #5 in a singledirection.

Here, the HDMI transmitter 81 performs the TMDS coding to the data to betransmitted through the TMDS channels #0 to #2. However, the HDMItransmitter 81 performs ANSI 8B10B coding which can extract a clock tothe data to be transmitted through the TMDS channels #3 to #5 in thepresent embodiment. The ANSI 8B10B coding is 8 bit/10 bit conversioncoding similarly to the TMDS coding.

The ANSI 8B10B coding can recognize each 8-bit data boundary from thetransmission data by appropriately inserting a certain pattern and alsocan directly extract a transmission clock. Also, the ANSI 8B10B codingis complete DC free coding and in which run-length is secured, and thedifferential signal can be AC coupled.

The HDMI receiver 82 of the data receiving unit 122 receives thedifferential signal corresponding to the video data and the differentialsignal corresponding to the audio data and the control data transmittedfrom the data transmitting unit 112 in a single direction through theTMDS channels #0 to #5. In this case, the HDMI receiver 82 extracts aclock from the reception data of either one of the TMDS channels #4 and#5, the TMDS channel #5 in the present embodiment, and the HDMI receiver82 receives the data of the TMDS channels #0 to #5 synchronously withthe clock.

Furthermore, the transmission channels of the HDMI system includetransmission channels referred to as a display data channel (DDC) and aCEC line in addition to the TMDS channels and the TMDS clock channel.The DDC includes two signal lines, which are not shown, included in thecable 200. The DDC is used to read enhanced extended displayidentification data (E-EDID) from the data receiving unit 122 by thedata transmitting unit 112.

That is, in addition to the HDMI receiver 82, the data receiving unit122 includes an EDID ROM (EEPROM) for storing E-EDID which is capabilityinformation on the configuration/capability of the data receiving unit122. The data transmitting unit 112, for example, reads the E-EDID fromthe data receiving unit 122 connected via the cable 200 via the DDC inresponse to a request from the control unit 113.

The data transmitting unit 112 transmits the read E-EDID to the controlunit 113. The control unit 113 stores the E-EDID in a flash ROM or aDRAM which is not shown. The control unit 113 can recognize a setting ofthe capability of the data receiving unit 122 on the basis of theE-EDID. For example, the control unit 113 recognizes whether the sinkdevice 120 including the data receiving unit 122 is compliant with thenew HDMI in addition to the current HDMI. The CEC line includes a singlesignal line, which is not shown, included in the cable 200 and is usedto bidirectionally transmit control data between the data transmittingunit 112 and the data receiving unit 122.

Also, the cable 200 includes a line (HPD line) connected to a pinreferred to as a hot plug detect (HPD). The source device uses the HPDline to detect the connection of the sink device. Furthermore, the HPDline is also used as a HEAC-line forming a bidirectional communicationpath. Also, the cable 200 includes a power supply line (+5 V Power Line)used to supply power from the source device to the sink device. Inaddition, the cable 200 further includes a utility line. The utilityline is also used as a HEAC+ line forming a bidirectional communicationpath.

FIG. 5 is a diagram of an exemplary configuration of the HDMItransmitter 81. The HDMI transmitter 81 includes a 6-lane (6-channel)mapper 11, a TMDS encoder 12, changeover switches 13 and 14, an 8B10Bencoder 15, a multiplier 16, and a changeover switch 17.

The mapper 11 performs mapping processing to video data, packetizedaudio data and control data, and vertical and horizontal synchronizationsignals to be input and outputs the data of the data channels #0 to #5.Also, the mapper 11 outputs a pixel clock to be input as a TMDS clock.The TMDS encoder 12 synchronizes the data of the data channels #0 to #2output from the mapper 11 with the TMDS clock output from the mapper 11and performs encode processing with the TMDS coding to the obtaineddata. Then, the TMDS encoder 12 obtains transmission data of the TMDSchannels #0 to #2.

The 8B10B encoder 15 performs encode processing with the ANSI 8B10Bcoding to the data of the data channels #3 to #5 output from the mapper11.

Also, the changeover switch 13 switches the data of the data channel #4output from the 8B10B encoder 15 with the ground and outputs it.Switching of the changeover switch 13 is controlled on the basis of aswitching control signal SWC. The changeover switch 13 outputs theground in the operation mode of the current HDMI and outputs the data ofthe data channel #4 in the operation mode of the new HDMI.

Also, the changeover switch 14 selectively switches the data of the datachannel #5 output from the 8B10B encoder 15 with the ground and outputsit. Switching of the changeover switch 14 is controlled on the basis ofthe switching control signal SWC. The changeover switch 14 outputs theground in the operation mode of the current HDMI and outputs the data ofthe data channel #5 in the operation mode of the new HDMI.

The multiplier 16 generates a bit clock by 10 multiples the input pixelclock and supplies the bit clock to the 8B10B encoder 15. The changeoverswitch 17 selectively switches the coding result of the data channel #3output from the 8B10B encoder 15 with the TMDS clock and transmits it asthe transmission data of the TMDS channel #3 (TMDS clock channel).Switching of the changeover switch 17 is controlled on the basis of theswitching control signal SWC. The changeover switch 17 outputs the TMDSclock in the operation mode of the current HDMI and outputs the codingresult of the data channel #3 in the operation mode of the new HDMI.

An operation of the HDMI transmitter 81 illustrated in FIG. 5 isdescribed. An operation of the HDMI transmitter 81 in the operation modeof the current HDMI is described first. The data of the data channels #0to #2 and the TMDS clock are obtained from the mapper 11. The data ofthe data channels #0 to #2 is supplied to the TMDS encoder 12.

The TMDS encoder 12 synchronizes the data of the data channels #0 to #2with the TMDS clock and performs the encode processing with the TMDScoding to the synchronized data. Then, the TMDS encoder 12 obtains thetransmission data of the TMDS channels #0 to #2. Also, the TMDS clockoutput from the mapper 11 is used as the transmission data of the TMDSclock channel (TMDS channel #3) via the changeover switch 17.

Next, an operation in the operation mode of the new HDMI is described.The data of the data channels #0 to #5 and the TMDS clock are obtainedfrom the mapper 11. The data of the data channels #0 to #2 is suppliedto the TMDS encoder 12. The TMDS encoder 12 synchronizes the data of thedata channels #0 to #2 with the TMDS clock and performs the encodeprocessing with the TMDS coding to the synchronized data. Then, the TMDSencoder 12 obtains the transmission data of the TMDS channels #0 to #2.

Also, the data of the data channels #3 to #5 is supplied to the 8B10Bencoder 15. The 8B10B encoder 15 synchronizes the data of the datachannels #3 to #5 with the bit clock and performs encode processing withthe ANSI 8B10B coding to the obtained data. Then, the 8B10B encoder 15obtains the transmission data of the TMDS channels #3 to #5.

FIG. 6 is a diagram of an exemplary configuration of the HDMI receiver82. Note that this is an example of a case where the data receiving unit122 of the sink device 120 is compliant with both the current HDMI andthe new HDMI. The HDMI receiver 82 includes a TMDS decoder 21,changeover switches 22 to 24, an 8B10B decoder 25, a clock extractor 26,a divider 27, a changeover switch 28, and a 6-lane (6-channel) demapper29.

The TMDS decoder 21 performs decode processing with the TMDS coding tothe reception data of the TMDS channels #0 to #2 and obtains the data ofthe data channels #0 to #2. The changeover switch 22 sorts and outputsreception data of the TMDS channel #3 (TMDS clock channel). Switching ofthe changeover switch 22 is controlled on the basis of the switchingcontrol signal SWC. The changeover switch 22 outputs the data to theside of the TMDS clock in the operation mode of the current HDMI andoutputs the data to the side of the data channel #3 in the operationmode of the new HDMI.

The changeover switch 23 sorts and outputs reception data of the TMDSchannel #4. Switching of the changeover switch 23 is controlled on thebasis of the switching control signal SWC. The changeover switch 23outputs the data to the side of the ground in the operation mode of thecurrent HDMI and outputs the data to the side of the data channel #4 inthe operation mode of the new HDMI. Also, the changeover switch 24 sortsand outputs reception data of the TMDS channel #5. Switching of thechangeover switch 24 is controlled on the basis of the switching controlsignal SWC. The changeover switch 24 outputs the data to the side of theground in the operation mode of the current HDMI and outputs the data tothe side of the data channel #5 in the operation mode of the new HDMI.

The 8B10B decoder 25 performs decode processing with the ANSI 8B10Bcoding to the data respectively output from the changeover switches 22to 24 to the sides of the data channels #3 to #5 and obtains data of thedata channels #3 to #5.

The clock extractor 26 extracts a bit clock from the data output fromthe changeover switch 24 to the side of the data channel #5 and suppliesthe bit clock to the 8B10B decoder 25. The divider 27 divides the bitclock extracted by the clock extractor 26 into 1/10 to obtain a TMDSclock (pixel clock).

The changeover switch 28 selectively switches the TMDS clock (pixelclock) output from the changeover switch 22 to the side of the TMDSclock and the TMDS clock obtained by the divider 27 and supplies it tothe TMDS decoder 21. Switching of the changeover switch 28 is controlledon the basis of the switching control signal SWC. The changeover switch28 selects the TMDS clock output from the changeover switch 22 in theoperation mode of the current HDMI and selects the TMDS clock obtainedby the divider 27 in the operation mode of the new HDMI.

The demapper 29 performs demapping processing to the data of the datachannels #0 to #2 obtained by the TMDS decoder 21, the TMDS clock (pixelclock) selected by the changeover switch 28, and the data of the datachannels #3 to #5 obtained by the 8B10B decoder 25 and obtains videodata, packetized audio data and control data, vertical and horizontalsynchronization signals, and a pixel clock. The demapper 29 performs theprocessing reverse to that of the mapper 11 of the HDMI transmitter 81in FIG. 5.

An operation of the HDMI receiver 82 illustrated in FIG. 6 is described.An operation of the HDMI transmitter 81 in the operation mode of thecurrent HDMI is described first. In this case, the TMDS channels #0 to#2 receive the data, and also the TMDS channel #3 (TMDS clock channel)receives the TMDS clock. The reception data of the TMDS channels #0 to#2 is supplied to the TMDS decoder 21.

The TMDS decoder 21 synchronizes the reception data of the TMDS channels#0 to #2 with the TMDS clock and performs the decode processing with theTMDS coding to the synchronized data. Then, the TMDS decoder 21 obtainsthe data of the data channels #0 to #2. The data of the data channels #0to #2 is supplied to the demapper 29.

Also, the TMDS clock received by the TMDS channel #3 (TMDS clockchannel) is supplied to the demapper 29 via the changeover switches 22and 28. The demapper 29 performs demapping processing to the data of thedata channels #0 to #2 and the TMDS clock (pixel clock) and obtainsvideo data, packetized audio data and control data, vertical andhorizontal synchronization signals, and a pixel clock.

Next, an operation in the operation mode of the new HDMI is described.In this case, the TMDS channels #0 to #5 receive the data. The receptiondata of the TMDS channels #0 to #2 is supplied to the TMDS decoder 21.The TMDS decoder 21 synchronizes the reception data of the TMDS channels#0 to #2 with the TMDS clock and performs the decode processing with theTMDS coding to the synchronized data. Then, the TMDS decoder 21 obtainsthe data of the data channels #0 to #2. The data of the data channels #0to #2 is supplied to the demapper 29.

Also, the reception data of the TMDS channels #3 to #5 is supplied tothe 8B10B decoder 25 respectively via the changeover switches 22 to 24.Also, the reception data of the TMDS channel #5 is supplied to the clockextractor 26, and a bit clock is extracted from the supplied data. Thebit clock is supplied to the divider 27 and the 8B10B decoder 25.

The 8B10B decoder 25 synchronizes the reception data of the TMDSchannels #3 to #5 with the bit clock and performs decode processing withthe ANSI 8B10B coding to the synchronized data. Then, the data of thedata channels #3 to #5 is obtained. The data of the data channels #3 to#5 is supplied to the demapper 29.

Also, the divider 27 divides the bit clock into 1/10 to generate a TMDSclock (pixel clock). The TMDS clock is supplied to the TMDS decoder 21via the changeover switch 28. The demapper 29 performs demappingprocessing to the data of the data channels #0 to #5 and the TMDS clock(pixel clock) and obtains video data, packetized audio data and controldata, vertical and horizontal synchronization signals, and a pixelclock.

FIG. 7 is a diagram of an exemplary structure of TMDS transmission data.In FIG. 7, periods of various transmission data in a case where imagedata of which an aspect ratio is B pixel×A line is transmitted in theTMDS channels #0 to #2 or the TMDS channels #0 to #5 are illustrated. Avideo field where the transmission data is transmitted in the TMDSchannel of the HDMI includes three kinds of periods corresponding to thekinds of the transmission data. The three kinds of periods are a VideoData period, a Data Island period, and a Control period.

Here, the video field period is a period from a rising edge (activeedge) of one vertical synchronizing signal to a rising edge of a nextvertical synchronizing signal. The video field period is divided intothree periods, i.e., a horizontal blanking period, a vertical blankingperiod, and an active video period. The Video Data period which is aperiod in the video field period other than the horizontal blankingperiod and the vertical blanking period is allocated to the active videoperiod. In the Video Data period, data of an active pixel, of which anaspect ratio is B pixel×A line, for forming uncompressed image data forone screen is transmitted.

The Data Island period and the Control period are respectively allocatedto the horizontal blanking period and the vertical blanking period. Inthe Data Island period and the Control period, auxiliary data istransmitted. That is, the Data Island period is allocated to a part ofthe horizontal blanking period and the vertical blanking period. In theData Island period, for example, a packet of audio data, which does notrelate to the control, of the auxiliary data is transmitted. The Controlperiod is allocated to the other part of the horizontal blanking periodand the vertical blanking period. In the Control period, for example, avertical synchronizing signal, a horizontal synchronization signal, anda control packet which relate to the control of the auxiliary data aretransmitted.

Here, a pin assignment of the receptacle 111 is described. A pinassignment (type A) of the current HDMI is described first. The pinassignment of the current HDMI forms a first pin assignment. FIG. 8(a)is a diagram of the pin assignment of the current HDMI. TMDS Data #i+and TMDS Data #i− which are differential signals of the TMDS channel #i(i=0 to 2) are transmitted through two lines which are differentiallines. Pins (pins having numbers of 7, 4, and 1) are allocated to theTMDS Data #i+, and pins (pins having numbers of 9, 6, and 3) areallocated to the TMDS Data #i−. Furthermore, pins having pin numbers of8, 5, and 2 are allocated to TMDS Data #i Shield (i=0 to 2).

A TMDS Clock+ and a TMDS Clock− which are differential signals of theTMDS clock channel are transmitted through two lines which are thedifferential lines. A pin having a pin number of 10 is allocated to theTMDS Clock+, a pin having a pin number of 12 allocated to the TMDSClock−. Furthermore, a pin having a pin number of 11 is allocated to theTMDS Clock Shield.

Also, a CEC signal which is data for control is transmitted through aCEC line. A pin having a pin number of 13 is allocated to the CECsignal. Also, a serial data (SDA) signal used to read the E-EDID istransmitted through an SDA line. A pin having a pin number of 16 isallocated to an SDA signal. Also, a serial clock signal (SCL) which is aclock signal used for synchronization at the time oftransmitting/receiving the SDA signal is transmitted through an SCLline. A pin having a pin number of 15 is allocated to the SCL.Furthermore, the DDC line includes the SDA line and the SCL line.

Also, a pin having a pin number of 19 is allocated to HPD/HEAC−. Also, apin having a pin number of 14 is allocated to utility/HEAC+. Also, a pinhaving a pin number of 17 is allocated to DDC/CEC Ground/HEAC Shield. Inaddition, a pin having a pin number of 18 is allocated to a power supply(+5 V Power).

Next, a pin assignment of the new HDMI is described. The pin assignmentof the new HDMI forms a second pin assignment. FIG. 8(b) is a diagram ofthe pin assignment of the new HDMI. The TMDS Data #i+ and the TMDS Data#i− which are the differential signals of the TMDS channels #i (i=0 to5) are transmitted through two lines which are differential lines. Pins(pins having pin numbers of 7, 4, 1, 10, 8, and 2) are allocated to theTMDS Data #i+, and pins (pins having pin numbers of 9, 6, 3, 12, 11, and5) are allocated to the TMDS Data #i−.

Also, a CEC signal which is data for control is transmitted through aCEC line. A pin having a pin number of 13 is allocated to the CECsignal. Also, a serial data (SDA) signal used to read the E-EDID istransmitted through an SDA line. A pin having a pin number of 16 isallocated to an SDA signal. Also, a serial clock signal (SCL) which is aclock signal used for synchronization at the time oftransmitting/receiving the SDA signal is transmitted through an SCLline. A pin having a pin number of 15 is allocated to the SCL.Furthermore, the DDC line includes the SDA line and the SCL line.

Also, a pin having a pin number of 19 is allocated to HPD/HEAC−. Also, apin having a pin number of 14 is allocated to utility/HEAC+. Also, a pinhaving a pin number of 17 is allocated to DDC/CEC Ground/HEAC Shield. Inaddition, a pin having a pin number of 18 is allocated to a power supply(+5 V Power).

As described above, in the new HDMI pin assignment (refer to FIG. 8(b)),terminals (pins having the pin numbers of 2, 5, 8, and 11) which areused as shield terminals in the current HDMI pin assignment (refer toFIG. 8(a)) are used as data terminals. Also, in the new HDMI pinassignment, terminals (pins having pin numbers of 10 and 12) used assignal terminals of the differential signal of the clock signal in thecurrent HDMI pin assignment are used as data terminals.

The data transmitting unit 112 of the source device 110 selects thecurrent HDMI pin assignment illustrated in FIG. 8(a) when operated inthe operation mode of the current HDMI and selects the new HDMI pinassignment illustrated in FIG. 8(b) when operated in the operation modeof the new HDMI. Note that the pin assignment of the receptacle 111 ofthe source device 110 has been described above. Although the descriptionis omitted, the above description is similarly applied to the pinassignment of the receptacle 121 of the sink device 120 in a case wherethe data receiving unit 122 of the sink device 120 is compliant withboth the current HDMI and the new HDMI.

FIGS. 9(a) and 9(b) are diagrams of the pin arrangements of thereceptacle 111 of the source device 110. FIG. 9(a) is a diagram of thepin arrangement of the current HDMI, and FIG. 9(b) is a diagram of thepin arrangement of the new HDMI. Furthermore, when the current HDMI pinassignment is selected as the pin assignment of the receptacle 111, thepins having the pin numbers of 2, 5, 8, and 11 are grounded in thesource device 110 and the sink device 120, or grounded in the sinkdevice 120 and in a high impedance state in the source device 110, or ina high impedance state in the sink device 120 and grounded in the sourcedevice 110. Furthermore, although the description is omitted, the abovedescription is similarly applied to the pin arrangement of thereceptacle 121 of the sink device 120 in a case where the data receivingunit 122 of the sink device 120 is compliant with both the current HDMIand the new HDMI.

FIG. 10(a) is a diagram of an exemplary structure of the current HDMIcable used as the cable 200. In the current HDMI cable, a shieldedtwisted pair part includes three data line pairs to obtain respectivecharacteristics. Also, the shielded twisted pair part includes a clockline pair and a line pair of utility and HPD for a HEAC function.

FIG. 10(b) is a diagram of an exemplary structure of the shieldedtwisted pair part. The shielded twisted pair part includes two electricwires 3 and a drain line 4 covered with a shield member 5. Furthermore,in the electric wire 3, a core wire 1 is covered with a covering part 2.

In the current HDMI cable, the drain line included in each shieldedtwisted pair part of the data and the clock is connected to a pin of aplug attached to the end of the cable. In this case, each drain line isconnected to a pin (terminal) corresponding to each shield terminal(shield pins having pin numbers 2, 5, 8, and 11) of the receptacle(current HDMI pin arrangement). The shield terminals are grounded in thesource device 110 and the sink device 120. Accordingly, the drain linefor configuring each shielded twisted pair part of the data and theclock is grounded in a state where the plug is connected to thereceptacle (current HDMI pin arrangement).

FIG. 11 is a diagram of an exemplary structure of a new HDMI cable usedas the cable 200. In the new HDMI cable, a shielded twisted pair partincludes six data line pairs to obtain respective characteristics. Also,the shielded twisted pair part includes a line pair of utility and HPDfor a HEAC function.

The new HDMI cable has more copper wires to be connected than thecurrent HDMI cable (refer to FIG. 10(a)). In the new HDMI cable, a drainline for configuring each shielded twisted pair part connected withdedicated pins of the plugs at both ends of the cable is connected to ametal shell of the plug. This opens a pin for shield and prevents anincrease in the number of necessary pins of the plug. The plug in thenew HDMI cable is similar to the plug of the current HDMI cable. In thisway, when the drain line for configuring each shielded twisted pair partis connected to the metal shell of the plug, the shield of thedifferential pair line can be secured by connecting the shell of thereceptacle, to which the plug is inserted, to a ground level.

“Operation Mode Control of Current HDMI and New HDMI”

Next, control of the operation mode of the control unit 113 in thesource device 110 is further described. As described above, the controlunit 113 controls the data transmitting unit 112 to operate in theoperation mode of the new HDMI when it is determined that the cable 200is compliant with the new HDMI and the sink device 120 is compliant withthe new HDMI. Also, the control unit 113 controls the data transmittingunit 112 to operate in the operation mode of the current HDMI otherwise.

FIG. 12 is a flowchart of a procedure for controlling the operation modeby the control unit 113. The control unit 113 starts processing in stepST1, and after that, the control unit 113 starts processing in step ST2.The control unit 113 determines in step ST2 whether the source device110, that is, the data transmitting unit 112 is compliant with the newHDMI. Since the control unit 113 previously has the capabilityinformation of the source device 110 (data transmitting unit 112) wherethe control unit 113 exists, the control unit 113 can easily make theabove determination. Furthermore, in the present embodiment, since it isobvious that the source device 110 is compliant with the new HDMI, thecontrol unit 113 may omit the determination processing in step ST2.

When it is determined that the source device 110 is compliant with thenew HDMI, the control unit 113 determines in step ST3 whether the sinkdevice 120, that is, the data receiving unit 122 is compliant with thenew HDMI. This determination is described in detail below. When it isdetermined that the sink device 120 is compliant with the new HDMI, thecontrol unit 113 starts processing in step ST4. In step ST4, the controlunit 113 determines whether the cable 200 is compliant with the newHDMI. This determination is described in detail below.

When it is determined that the cable 200 is compliant with the new HDMI,the control unit 113 starts processing in step ST5. In step ST5, thecontrol unit 113 controls the data transmitting unit 112 to operate inthe operation mode of the new HDMI. Also, when it is determined in stepsST2, ST3, and ST4 that the source device 110, the sink device 120, andthe cable 200 are not compliant with the new HDMI, the control unit 113starts processing in step ST6. In step ST6, the control unit 113controls the data transmitting unit 112 to operate in the operation modeof the current HDMI.

For example, when determining in step ST3 that the sink device 120 iscompliant with the new HDMI, the control unit 113 transmits the finaldetermination result on the operation mode to the sink device 120 viathe cable 200. For example, the determination result is transmittedthrough a line such as the CEC line before the data transmission fromthe source device 110. In the sink device 120, the control unit 123controls the data receiving unit 122 to operate in an operation modesame as the operation mode of the data transmitting unit 112 of thesource device 110 on the basis of the determination result on theoperation mode from the source device 110.

Also, when controlling the data transmitting unit 112 to operate in theoperation mode of the new HDMI in step ST5, the control unit 113 maycontrol an UI screen indicating the above control to be displayed on adisplay unit (display) as illustrated in FIG. 13(a). A user can easilyrecognize that the source device 110 is connected to the sink device 120with the new HDMI from the UI screen. Note that the display unit(display) where the UI screen is displayed is a display unit (display),which is not shown, provided in the source device 110 or a display unit(display), which is not shown, provided in the sink device 120. This issimilarly applied to the following UI displays.

Also, when determining that the cable 200 is not compliant with the newHDMI in step ST4 and starts the processing in step ST6, for example, thecontrol unit 113 may control the UI screen indicating that to bedisplayed on a display unit (display) as illustrated in FIG. 13(c). Fromthe UI screen, the user can easily recognize that the source device 110and the sink device 120 are compliant the new HDMI and that the cable200 is not compliant with the new HDMI. Measures such as replacement ofthe cable 200 with the new HDMI cable can be taken.

Also, in the procedure in the flowchart illustrated in FIG. 12, whendetermining that the cable 200 is compliant with the new HDMI in stepST4, the control unit 113 immediately starts step ST5 and controls thedata transmitting unit 112 to operate in the operation mode of the newHDMI. However, when determining that the cable 200 is compliant with thenew HDMI in step ST4 by transmitting/receiving a command through a linesuch as the CEC before data transmission, the control unit 113 may makethe user select either one of the new HDMI or the current HDMI(traditional HDMI).

In this case, the control unit 113 controls the UI screen which makesthe user select one of the HDMIs to be displayed on the display unit(display) as illustrated in FIG. 13(b). The user selects either one ofthe new HDMI or the current HDMI on the basis of the UI screen. In FIG.13(b), a state is illustrated in which the “new HDMI” is selected. Thecontrol unit 113 controls the data transmitting unit 112 to operate inthe operation mode of the new HDMI or the current HDMI according to theselection by the user.

FIG. 14 is a flowchart of a procedure for controlling the operation modeby the control unit 113 in this case. In FIG. 14, parts corresponding tothose in FIG. 12 are denoted with the same reference numerals, and thedescription on the corresponding parts is omitted. When control unit 113determines that the cable 200 is compliant with the new HDMI in stepST4, the procedure proceeds to step ST7. In step ST7, the control unit113 controls the display unit (display) to display the UI screen toselect either one of the new HDMI or the current HDMI. The display ofthe UI may be transmitted as a video signal by the source device 110through the transmission path 200, and the sink device 120 may instructthe display to display the UI.

Subsequently, the control unit 113 starts processing in step ST8. Instep ST8, the control unit 123 informs the control unit 113 of anoperation by the user with a remote controller through a line such asthe CEC so that the control unit 113 determines which one of the newHDMI and the current HDMI has been selected by the user. When the userhas selected the new HDMI, the control unit 113 controls the datatransmitting unit 112 to operate in the operation mode of the new HDMIin step ST5. On the other hand, when the user has selected the currentHDMI, the control unit 113 controls the data transmitting unit 112 tooperate in the operation mode of the current HDMI (traditional HDMI) instep ST6.

“Determination Whether Sink Device is Compliant with New HDMI”

A method for determining by the control unit 113 whether the sink device120 is compliant with the new HDMI is described. For example, a firstdetermination method and a second determination method below areexemplified as the determination method.

“First Determination Method”

The control unit 113 determines whether the sink device 120 is compliantwith the new HDMI on the basis of the EDID read from the sink device 120with the DDC line (SDA line and SCL line) of the cable 200. The EDID hasa data structure specified by a format. It is assumed that flaginformation be newly defined in a predetermined position in the EDID.The flag information indicates whether the sink device 120 is compliantwith the new HDMI (new transmission).

FIG. 15 is an example of flag information newly defined in the EDID.Originally, the EDID is a data structure indicating capabilities ofvarious sink devices 120. For easy description, bites of the EDIDrelating to the present invention are illustrated in FIG. 15, and FIG.15 is simplified by illustrating minimum components. In a second bit,one-bit flag information “New Rx Sink” is written which indicateswhether the sink device 120 is compliant with the new HDMI. Also, in afirst bit, one-bit flag information “New Cable” indicating whether thecable 200 is compliant with the new HDMI is newly defined.

When the one-bit flag information “New Rx Sink” exists in the EDID readfrom the sink device 120, the control unit 113 determines that the sinkdevice 120 is compliant with the new HDMI. That is, when the sink device120 is compliant with the current HDMI, the one-bit flag information“New Rx Sink” does not exist in the EDID read from the sink device 120.

“Second Determination Method”

The control unit 113 communicates with the sink device 120 via the cable200 to determine whether the sink device 120 is compliant with the newHDMI. For example, the control unit 113 confirms whether the sink device120 is compliant with the new HDMI with a command base by using the CECline.

Also, for example, the control unit 113 communicates with the sinkdevice 120 by using the bidirectional communication path (HEAC function)including the utility line and the HPD line to determine whether thesink device 120 is compliant with the new HDMI. In addition, forexample, the control unit 113 confirms whether the sink device 120 iscompliant with the new HDMI by using an unused line such as a utilityline and receiving/transmitting some signals until the transmissionbecomes available.

“Determination Whether Cable is Compliant with New HDMI”

Next, a method for determining by the control unit 113 whether the cable200 is compliant with the new HDMI is described. As the determinationmethod, various methods can be considered as disclosed in JapanesePatent Application Laid-Open No. 2012-250673. One example is describedbelow.

In a case of this example, as illustrated in FIG. 16, the new HDMI cableincludes a large scale integration (LSI), for example, in the plug. Forexample, in a state where +5 V is supplied from the source device 110,the sink device 120 requires an output to the LSI by a CEC protocolwhile the HPD is lowered to L. Note that the sink device 120 in thiscase is a sink device being compliant with the new HDMI. The LSI reportsa register value mounted in the LSI (indicating that the LSI iscompliant with the new HDMI and cable characteristics data such as atransmittable data band) to the sink device 120 with the CEC protocol inresponse to the output request from the sink device 120.

The sink device 120 adds the information reported from the LSI to theEDID. After the addition, the sink device 120 instructs the sourcedevice 110 to read the EDID by changing the HPD to H. The control unit113 determines whether the cable 200 is compliant with the new HDMI onthe basis of the EDID read from the sink device 120. That is, when theinformation indicating that the cable 200 is compliant with the new HDMIis included in the EDID, the control unit 113 determines that the cable200 is compliant with the new HDMI.

Note that the sink device 120 requests the LSI to output by the CECprotocol in the above description. However, it can be also consideredthat the source device 110 requests the LSI to output by the CECprotocol and directly receives the report of the register value(indicating that the LSI is compliant with the new HDMI and cablecharacteristics data such as a transmittable data band) from the LSI.

As described above, in the AV system 10 illustrated in FIG. 1, the datatransmitting unit 112 of the source device 110 has the operation mode ofthe new HDMI mode in addition to the operation mode of the current HDMI.Here, the number of the differential signal channels to transfer thedigital signal such as video data is three in the current HDMI and sixin the new HDMI. Therefore, signal transmission with a high data ratecan be performed by using the new HDMI. Also, when the sink device 120and the cable 200 are not compliant with the new HDMI, a backwardcompatibility is secured by using the current HDMI (traditional HDMI).

Also, in the AV system 10 illustrated in FIG. 1, TMDS coding is employedas coding for the TMDS channels #0 to #2 in the new HDMI mode.Therefore, it is preferable that the source device 110 perform the TMDScoding as the TMDS channels #0 to #2. Reduction in a design load can beexpected, and in addition, coding with less unnecessary radiation can beemployed.

2. Variation

Note that the number of the differential signal channels to transmit thedigital signal such as the video data in the current HDMI is three, andthe number of differential signal channels is six in the new HDMI, inthe above embodiment. However, the number of the differential signalchannels to transmit the digital signal such as the video data is notlimited to six and may be four, five, or seven. For example, it isassumed that the number of the differential signal channels to transmitthe digital signal such as the video data be five and a clock frequencybe increased to about 1.2 times. This enables to obtain a data transferspeed equivalent to that in a case of the six differential signalchannels.

Also, in the above embodiment, the present technology is applied to theAV system in which the source device and the sink device are connectedby an HDMI standard digital interface. The present technology can besimilarly applied to an AV system which is connected by other similardigital interfaces.

Also, the technology may have a following configuration.

(1) A transmission apparatus including:

a digital signal transmission unit configured to transmit a digitalsignal to which coding has been performed to an external device by adifferential signal through a plurality of channels via a transmissionpath, wherein

the digital signal transmission unit transmits a digital signal to whichfirst coding has been performed and from which clock extraction is notavailable through a part of the plurality of channels and transmits adigital signal to which second coding has been performed and from whichclock extraction is available through the other channels of theplurality of channels.

(2) The transmission apparatus according to (1), wherein

the first coding is TMDS coding.

(3) The transmission apparatus according to (1) or (2), wherein

both the first coding and the second coding are 8 bit/10 bit conversioncoding.

(4) The transmission apparatus according to any one of (1) to (3),wherein

the transmission path is an HDMI cable, and

the number of a part of the channels is three, and the number of otherchannels is three.

(5) A transmission method including:

a digital signal transmission step of transmitting a digital signal towhich coding has been performed to an external device by a digitalsignal transmission unit by using a differential signal through aplurality of channels via a transmission path, wherein

in the digital signal transmission step, a digital signal to which firstcoding has been performed and from which clock extraction is notavailable is transmitted through a part of the plurality of channels,and a digital signal to which second coding has been performed and fromwhich clock extraction is available is transmitted through the otherchannels of the plurality of channels.

(6) A reception apparatus including:

a digital signal reception unit configured to receive a digital signalto which coding has been performed from an external device by adifferential signal through a plurality of channels via a transmissionpath, wherein

the digital signal reception unit receives a digital signal to whichfirst coding has been performed and from which clock extraction is notavailable through a part of the plurality of channels and receives adigital signal to which second coding has been performed and from whichclock extraction is available through other channels of the plurality ofchannels, and

the reception apparatus further including:

a processing unit configured to process the digital signal receivedthrough the plurality of channels on the basis of the clock extractedfrom the digital signal received through any one of the other channels.

(7) A reception method including:

a digital signal receiving step of receiving a digital signal to whichcoding has been performed from an external device by a digital signalreception unit by a differential signal through a plurality of channelsvia a transmission path, wherein

in the digital signal receiving step, a digital signal to which firstcoding has been performed and from which clock extraction is notavailable is received through a part of the plurality of channels, and adigital signal to which second coding has been performed and from whichclock extraction is available is received through the other channels ofthe plurality of channels, and

the reception method further including:

a processing step of processing the digital signal received through theplurality of channels on the basis of the clock extracted from thedigital signal received through any one of the other channels.

(8) A transmission apparatus including:

a digital signal transmission unit configured to transmit a digitalsignal to which coding has been performed to an external device by adifferential signal through a plurality of channels via a transmissionpath, wherein

the digital signal transmission unit transmits the digital signal byselecting one of a first mode and a second mode,

the first mode is a mode for transmitting a digital signal to whichfirst coding has been performed and from which clock extraction is notavailable through a predetermined number of first channels andtransmitting a digital signal to which second coding has been performedand from which clock extraction is available through a predeterminednumber of second channels, and

the second mode is a mode for transmitting the digital signal to whichthe first coding has been performed through the predetermined number offirst channels and transmitting a clock through a single third channelcorresponding to any one of the predetermined number of second channels.

(9) The transmission apparatus according to (8), further including:

a mode determining unit configured to determine whether the externaldevice and the transmission path are compliant with the first mode; and

a control unit configured to control mode selection by the digitalsignal transmission unit on the basis of the determination by the modedetermining unit.

(10) The transmission apparatus according to (8) or (9), wherein

channels of the predetermined number of second channels other than thesingle channel corresponding to the third channel are AC coupled withthe transmission path.

(11) The transmission apparatus according to any one of (8) to (10),wherein

the first coding is TMDS coding.

(12) The transmission apparatus according to any one of (8) to (11),wherein

both the first coding and the second coding are 8 bit/10 bit conversioncoding.

(13) The transmission apparatus according to any one of (8) to (12),wherein

the transmission path is an HDMI cable, and

the number of the first channels is three, and the number of the secondchannels is three.

(14) A transmission method including:

a digital signal transmission step of transmitting a digital signal towhich coding has been performed to an external device by a digitalsignal transmission unit by a differential signal through a plurality ofchannels via a transmission path, wherein

in the digital signal transmission step, the digital signal istransmitted by selecting one of a first mode and a second mode,

the first mode is a mode for transmitting a digital signal to whichfirst coding has been performed and from which clock extraction is notavailable through a predetermined number of first channels andtransmitting a digital signal to which second coding has been performedand from which clock extraction is available through a predeterminednumber of second channels, and

the second mode is a mode for transmitting a digital signal to which thefirst coding has been performed through the predetermined number offirst channels and transmitting a clock through a single third channelcorresponding to any one of the predetermined number of second channels.

(15) A reception apparatus including:

a digital signal reception unit configured to receive a digital signalto which coding has been performed from an external device by adifferential signal through a plurality of channels via a transmissionpath, wherein

the digital signal reception unit receives the digital signal byselecting one of a first mode and a second mode,

the first mode is a mode for receiving a digital signal to which firstcoding has been performed and from which clock extraction is notavailable through a predetermined of number of first channels andreceiving a digital signal to which second coding has been performed andfrom which clock extraction is available through a predetermined numberof second channels, and

the second mode is a mode for receiving a digital signal to which thefirst coding has been performed through the predetermined number offirst channels and receiving a clock through a single third channelcorresponding to any one of the predetermined number of second channels,and

the reception apparatus further including:

a processing unit configured to process the digital signal receivedthrough the predetermined number of first channels and second channelson the basis of the clock extracted from the digital signal receivedthrough any one of the predetermined number of second channels in thefirst mode and process the digital signal received through thepredetermined number of first channels on the basis of the clockreceived through the third channel in the second mode.

(16) The reception apparatus according to (15), wherein

channels of the predetermined number of second channels other than thesingle channel corresponding to the third channel are AC coupled withthe transmission path.

(17) The reception apparatus according to (15) or (16), wherein

both the first coding and the second coding are 8 bit/10 bit conversioncoding.

(18) The reception apparatus according to any one of (15) to (17),wherein

the transmission path is an HDMI cable, and

the number of the first channels is three, and the number of the secondchannels is three.

(19) The reception apparatus according to any one of (15) to (18),further including:

a control unit configured to control mode selection by the digitalsignal transmission unit on the basis of control information transmittedfrom the external device.

(20) A reception method including:

a digital signal receiving step of receiving a digital signal to whichcoding has been performed from an external device by a digital signalreception unit by a differential signal through a plurality of channelsvia a transmission path, wherein

in the digital signal receiving step, the digital signal is received byselecting one of a first mode and a second mode,

the first mode is a mode for receiving a digital signal to which firstcoding has been performed and from which clock extraction is notavailable through a predetermined number of first channels and receivinga digital signal to which second coding has been performed and fromwhich clock extraction is available through a predetermined number ofsecond channels, and

the second mode is a mode for receiving a digital signal to which thefirst coding has been performed through the predetermined number offirst channels and receiving a clock through a single third channelcorresponding to any one of the predetermined number of second channels,and

the reception method further including:

a processing step of processing the digital signal received through thepredetermined number of first channels and second channels on the basisof the clock extracted from the digital signal received through any oneof the predetermined number of second channels in the first mode andprocessing the digital signal received through the predetermined numberof first channels on the basis of the clock received through the thirdchannel in the second mode.

REFERENCE SIGNS LIST

-   11 mapper-   12 TMDS encoder-   13, 14, 17 changeover switch-   15 8B10B encoder-   16 multiplier-   21 TMDS decoder-   22, 23, 24, 28 changeover switch-   25 8B10B decoder-   26 clock extractor-   27 divider-   29 demapper-   81 HDMI transmitter-   82 HDMI receiver-   100 AV system-   110 source device-   111 receptacle-   112 data transmitting unit-   113 control unit-   120 sink device-   121 receptacle-   122 data receiving unit-   123 control unit-   200 cable-   201, 202 plug

1. A transmission apparatus comprising: a digital signal transmissionunit configured to transmit a digital signal to which coding has beenperformed to an external device by a differential signal through aplurality of channels via a transmission path, wherein the digitalsignal transmission unit transmits a digital signal to which firstcoding has been performed and from which clock extraction is notavailable through a part of the plurality of channels and transmits adigital signal to which second coding has been performed and from whichclock extraction is available through the other channels of theplurality of channels.
 2. The transmission apparatus according to claim1, wherein the first coding is TMDS coding.
 3. The transmissionapparatus according to claim 1, wherein both the first coding and thesecond coding are 8 bit/10 bit conversion coding.
 4. The transmissionapparatus according to claim 1, wherein the transmission path is an HDMIcable, and the number of a part of the channels is three, and the numberof other channels is three.
 5. A transmission method comprising: adigital signal transmission step of transmitting a digital signal towhich coding has been performed to an external device by a digitalsignal transmission unit by using a differential signal through aplurality of channels via a transmission path, wherein in the digitalsignal transmission step, a digital signal to which first coding hasbeen performed and from which clock extraction is not available istransmitted through a part of the plurality of channels, and a digitalsignal to which second coding has been performed and from which clockextraction is available is transmitted through the other channels of theplurality of channels.
 6. A reception apparatus comprising: a digitalsignal reception unit configured to receive a digital signal to whichcoding has been performed from an external device by a differentialsignal through a plurality of channels via a transmission path, whereinthe digital signal reception unit receives a digital signal to whichfirst coding has been performed and from which clock extraction is notavailable through a part of the plurality of channels and receives adigital signal to which second coding has been performed and from whichclock extraction is available through other channels of the plurality ofchannels, and the reception apparatus further comprising: a processingunit configured to process the digital signal received through theplurality of channels on the basis of the clock extracted from thedigital signal received through any one of the other channels.
 7. Areception method comprising: a digital signal receiving step ofreceiving a digital signal to which coding has been performed from anexternal device by a digital signal reception unit by a differentialsignal through a plurality of channels via a transmission path, whereinin the digital signal receiving step, a digital signal to which firstcoding has been performed and from which clock extraction is notavailable is received through a part of the plurality of channels, and adigital signal to which second coding has been performed and from whichclock extraction is available is received through the other channels ofthe plurality of channels, and the reception method further comprising:a processing step of processing the digital signal received through theplurality of channels on the basis of the clock extracted from thedigital signal received through any one of the other channels.
 8. Atransmission apparatus comprising: a digital signal transmission unitconfigured to transmit a digital signal to which coding has beenperformed to an external device by a differential signal through aplurality of channels via a transmission path, wherein the digitalsignal transmission unit transmits the digital signal by selecting oneof a first mode and a second mode, the first mode is a mode fortransmitting a digital signal to which first coding has been performedand from which clock extraction is not available through a predeterminednumber of first channels and transmitting a digital signal to whichsecond coding has been performed and from which clock extraction isavailable through a predetermined number of second channels, and thesecond mode is a mode for transmitting the digital signal to which thefirst coding has been performed through the predetermined number offirst channels and transmitting a clock through a single third channelcorresponding to any one of the predetermined number of second channels.9. The transmission apparatus according to claim 8, further comprising:a mode determining unit configured to determine whether the externaldevice and the transmission path are compliant with the first mode; anda control unit configured to control mode selection by the digitalsignal transmission unit on the basis of the determination by the modedetermining unit.
 10. The transmission apparatus according to claim 8,wherein channels of the predetermined number of second channels otherthan the single channel corresponding to the third channel are ACcoupled with the transmission path.
 11. The transmission apparatusaccording to claim 8, wherein the first coding is TMDS coding.
 12. Thetransmission apparatus according to claim 8, wherein both the firstcoding and the second coding are 8 bit/10 bit conversion coding.
 13. Thetransmission apparatus according to claim 8, wherein the transmissionpath is an HDMI cable, and the number of the first channels is three,and the number of the second channels is three.
 14. A transmissionmethod comprising: a digital signal transmission step of transmitting adigital signal to which coding has been performed to an external deviceby a digital signal transmission unit by a differential signal through aplurality of channels via a transmission path, wherein in the digitalsignal transmission step, the digital signal is transmitted by selectingone of a first mode and a second mode, the first mode is a mode fortransmitting a digital signal to which first coding has been performedand from which clock extraction is not available through a predeterminednumber of first channels and transmitting a digital signal to whichsecond coding has been performed and from which clock extraction isavailable through a predetermined number of second channels, and thesecond mode is a mode for transmitting a digital signal to which thefirst coding has been performed through the predetermined number offirst channels and transmitting a clock through a single third channelcorresponding to any one of the predetermined number of second channels.15. A reception apparatus comprising: a digital signal reception unitconfigured to receive a digital signal to which coding has beenperformed from an external device by a differential signal through aplurality of channels via a transmission path, wherein the digitalsignal reception unit receives the digital signal by selecting one of afirst mode and a second mode, the first mode is a mode for receiving adigital signal to which first coding has been performed and from whichclock extraction is not available through a predetermined of number offirst channels and receiving a digital signal to which second coding hasbeen performed and from which clock extraction is available through apredetermined number of second channels, and the second mode is a modefor receiving a digital signal to which the first coding has beenperformed through the predetermined number of first channels andreceiving a clock through a single third channel corresponding to anyone of the predetermined number of second channels, and the receptionapparatus further comprising: a processing unit configured to processthe digital signal received through the predetermined number of firstchannels and second channels on the basis of the clock extracted fromthe digital signal received through any one of the predetermined numberof second channels in the first mode and process the digital signalreceived through the predetermined number of first channels on the basisof the clock received through the third channel in the second mode. 16.The reception apparatus according to claim 15, wherein channels of thepredetermined number of second channels other than the single channelcorresponding to the third channel are AC coupled with the transmissionpath.
 17. The reception apparatus according to claim 15, wherein boththe first coding and the second coding are 8 bit/10 bit conversioncoding.
 18. The reception apparatus according to claim 15, wherein thetransmission path is an HDMI cable, and the number of the first channelsis three, and the number of the second channels is three.
 19. Thereception apparatus according to claim 15, further comprising: a controlunit configured to control mode selection by the digital signaltransmission unit on the basis of control information transmitted fromthe external device.
 20. A reception method comprising: a digital signalreceiving step of receiving a digital signal to which coding has beenperformed from an external device by a digital signal reception unit bya differential signal through a plurality of channels via a transmissionpath, wherein in the digital signal receiving step, the digital signalis received by selecting one of a first mode and a second mode, thefirst mode is a mode for receiving a digital signal to which firstcoding has been performed and from which clock extraction is notavailable through a predetermined number of first channels and receivinga digital signal to which second coding has been performed and fromwhich clock extraction is available through a predetermined number ofsecond channels, and the second mode is a mode for receiving a digitalsignal to which the first coding has been performed through thepredetermined number of first channels and receiving a clock through asingle third channel corresponding to any one of the predeterminednumber of second channels, and the reception method further comprising:a processing step of processing the digital signal received through thepredetermined number of first channels and second channels on the basisof the clock extracted from the digital signal received through any oneof the predetermined number of second channels in the first mode andprocessing the digital signal received through the predetermined numberof first channels on the basis of the clock received through the thirdchannel in the second mode.